ABSTRACT: Genome characterization, prevalence and transmission mode of a novel picornavirus associated with the Threespine Stickleback (Gasterosteus aculeatus)
Project description:After the end of the last ice age, ancestrally marine threespine stickleback fish (Gasterosteus aculeatus) have undergone an adaptive radiation into freshwater environments throughout the Northern Hemisphere, creating an excellent model system for studying molecular adaptation and speciation. Stickleback populations are reproductively isolated to varying degrees, despite the fact that they can be crossed in the lab to produce viable offspring. Ecological and behavioral factors have been suggested to underlie incipient stickleback speciation. However, reproductive proteins represent a previously unexplored driver of speciation. As mediators of gamete recognition during fertilization, reproductive proteins both create and maintain species boundaries. Gamete recognition proteins are also frequently found to be rapidly evolving, and their divergence may culminate in reproductive isolation and ultimately speciation. As an initial investigation into the contribution of reproductive proteins to stickleback reproductive isolation, we characterized the egg coat proteome of threespine stickleback eggs. In agreement with other teleosts, we find that stickleback egg coats are comprised of homologs to the zona pellucida (ZP) proteins ZP1 and ZP3. We explore aspects of stickleback ZP protein biology, including glycosylation, disulfide bonding, and sites of synthesis, and find many substantial differences compared to their mammalian homologs. Furthermore, molecular evolutionary analyses indicate that ZP3, but not ZP1, has experienced positive Darwinian selection across teleost fish. Taken together, these changes to stickleback ZP protein architecture suggest that the egg coats of stickleback fish, and perhaps fish more generally, have evolved to fulfill a more protective functional role than their mammalian counterparts.
Project description:After the end of the last ice age, ancestrally marine threespine stickleback fish (Gasterosteus aculeatus) have undergone an adaptive radiation into freshwater environments throughout the Northern Hemisphere, creating an excellent model system for studying molecular adaptation and speciation. Stickleback populations are reproductively isolated to varying degrees, despite the fact that they can be crossed in the lab to produce viable offspring. Ecological and behavioral factors have been suggested to underlie incipient stickleback speciation. However, reproductive proteins represent a previously unexplored driver of speciation. As mediators of gamete recognition during fertilization, reproductive proteins both create and maintain species boundaries. Gamete recognition proteins are also frequently found to be rapidly evolving, and their divergence may culminate in reproductive isolation and ultimately speciation. As an initial investigation into the contribution of reproductive proteins to stickleback reproductive isolation, we characterized the egg coat proteome of threespine stickleback eggs. In agreement with other teleosts, we find that stickleback egg coats are comprised of homologs to the zona pellucida (ZP) proteins ZP1 and ZP3. We explore aspects of stickleback ZP protein biology, including glycosylation, disulfide bonding, and sites of synthesis, and find many substantial differences compared to their mammalian homologs. Furthermore, molecular evolutionary analyses indicate that ZP3, but not ZP1, has experienced positive Darwinian selection across teleost fish. Taken together, these changes to stickleback ZP protein architecture suggest that the egg coats of stickleback fish, and perhaps fish more generally, have evolved to fulfill a more protective functional role than their mammalian counterparts.
Project description:Many taxa have independently evolved genetic sex determination where a single gene located on a sex chromosome controls gonadal differentiation. The gene anti-Mullerian hormone (amh) has convergently evolved as a sex determination gene in numerous vertebrate species, but how this gene has repeatedly evolved this novel function is not well understood. In the threespine stickleback (Gasterosteus aculeatus), amh was duplicated onto the Y chromosome (amhy) ~22 million years ago. To determine whether amhy is the primary sex determination gene, we used CRISPR/Cas9 and transgenesis to show that amhy is necessary and sufficient for male sex determination, consistent with the function of a primary sex determination gene. We find that amhy contributes to a higher total dosage of amh early in development and likely contributes to differential germ cell proliferation key to sex determination. The creation of sex reversed lines also allowed us to investigate the genetic basis of secondary sex characteristics. Threespine stickleback have striking differences in behavior and morphology between sexes. Here we show one of the classic traits important for reproductive success, blue male nuptial coloration, is controlled by both sex-linked genetic factors as well as hormonal factors independent of sex chromosome genotype. This research establishes stickleback as a model to investigate how amh regulates gonadal development and how this gene repeatedly evolves novel function in sex determination. Analogous to the “four core genotypes” model in house mice, sex-reversed threespine stickleback offer a new vertebrate model for investigating the separate contributions of gonadal sex and sex chromosomes to sexual dimorphism.
2025-10-29 | GSE296766 | GEO
Project description:Genome characterization, prevalence and transmission mode of a novel picornavirus associated with the Threespine Stickleback (Gasterosteus aculeatus)
Project description:In this study, we used whole genome comparative oligonucleotide microarrays to investigate the brain transcriptomic response to predator cues using the threespine stickleback, Gasteroteus aculeatus. We showed that exposure to olfactory, visual and tactile cues of a predator (rainbow trout, Oncorhynchus mykiss) for six days resulted in subtle but significant transcriptomic changes in the brain of sticklebacks. Gene functional analysis and gene ontology (GO) enrichment revealed that the majority of the transcripts differentially expressed between the fish exposed to predator cues and the control group are primarily related to antigen processing and presentation (involving primarily the major histocompatibility complex (MHC)), transmission of synaptic signals, brain metabolic processes, gene regulation, or visual perception. Pathway analysis identified synaptic long-term depression, RAN signaling, relaxin signaling and phototransduction as the top four pathways that were over-represented.
Project description:Schistocephalus solidus is a cestode parasite that is thought to manipulate the behaviour of its threespine stickleback host Gasterosteus aculeatus. It has been hypothesized that the worm could liberate in its external environment “manipulation factors” that would ultimately interfere with the host’s physiology and behaviour. The objective of this project is to describe the whole proteomic content of the proteome and of the secretome of a putative manipulative parasite, Schistocephalus solidus, with the aim to identify proteins that could be involved in the behavioural perturbations of the threespine stickleback.
Project description:The three-spined stickleback (Gasterosteus aculeatus) is an important model organism for understanding the genetic basis of adaptation in response to ecological change. We used single nucleus RNA-sequencing (snRNA-seq) to define brain cell type composition and gene expression in adult and juvenile three-spined stickleback. These data will faciliate improved understanding of how the nervous system responds/adapts to environmental factors.
Project description:Adult female three-spined stickleback fish (Gasterosteus aculeatus) were exposed to 10 individual chemicals, 26 mixtures of these chemicals, or control conditions in a flow-through system for 4 days. Transcriptomics was performed on liver samples by microarray. The main aims were to determine molecular signatures induced by these chemicals in the three-spined stickleback, discover whether these persisted in chemical mixtures and identify non-additive molecular responses in chemical mixtures exposures.
Project description:In this study, we used whole genome comparative oligonucleotide microarrays to investigate the brain transcriptomic response to predator cues using the threespine stickleback, Gasteroteus aculeatus. We showed that exposure to olfactory, visual and tactile cues of a predator (rainbow trout, Oncorhynchus mykiss) for six days resulted in subtle but significant transcriptomic changes in the brain of sticklebacks. Gene functional analysis and gene ontology (GO) enrichment revealed that the majority of the transcripts differentially expressed between the fish exposed to predator cues and the control group are primarily related to antigen processing and presentation (involving primarily the major histocompatibility complex (MHC)), transmission of synaptic signals, brain metabolic processes, gene regulation, or visual perception. Pathway analysis identified synaptic long-term depression, RAN signaling, relaxin signaling and phototransduction as the top four pathways that were over-represented. Adult fish were placed in six different 26L tanks with three fish per tank in a partially recirculating flow-through system. Half of the tanks were assigned to the control group and the other half to the experimental group.10 samples were selected for microarray analysis. The ten samples comprised five biological replicates in the experimental group (fish exposed to predator cues) and five biological replicates in the control group (fish not exposed to predator cues), and were evenly distributed across tanks. The cDNA labeling (single color), hybridization, washing and scanning steps were performed in the NimbleGen microarray gene expression service department.